Laser tube processing

Ten out-of-the-box techniques save money, spur innovation

The Tube & Pipe Journal October/November 2003
November 20, 2003
By: David Gilmore

The introduction of lasers to the manufacturing process has changed the fabrication of tubing. Today, many manual processes can be replaced with laser processing techniques. Using the flexibility afforded by lasers, a bundle of raw tubing can be loaded into a laser tube cutter; parts can be cut with high accuracy, quality, and speed; and then finished parts from the machine can be sent directly to the final assembly.

Although many new applications are made possible by modern lasers, laser processing is not entirely new to tube production. Manufacturers have used lasers to cut tube and pipe since the late 1970s. At job shops most of this laser tube cutting was performed on flat sheet cutting laser systems equipped with optional rotary axes. Such systems employed simple rotary chuck add-ons with manual load and unload features and gave fabricators the flexibility to handle many different types of jobs.

However, as fabricators' volume and tube cutting needs increased, these manually loaded and unloaded systems quickly showed their limitations.

Dedicated tube cutting laser systems solved productivity issues for some, but custom-designed systems were not always reliable or cost-effective for the average job shop. Today, standardization of these machines has increased their reliability and reduced their cost.

With the integration of automated tube delivery and part removal, reliable fabrication of tubing has come of age. Projects that used to require several labor-intensive operations on different machines, long weld setup times, or seemingly impossible designs are now easily handled on a dedicated tube processing laser.

Entirely new designs and techniques can now be created thanks to the laser's capabilities.

1. Cut to Length
Lasers give you the ability to cut tubing–the first and most common tube processing application–with a high degree of accuracy and with no tool wear. They also provide the ability to change your cut length on the fly with no manual setup. Lasers can be set up to cut without producing burr, dross, or contamination, making them suitable for applications requiring a pristine surface inside the tubing.

Figure 1
Today's tube cutting laser systems can create angled cutoffs and coped cuts for tube-to-tube connections or structural joints.

2. Miters and Coped Cuts
Today's tube cutting laser systems can create angled cutoffs and coped cuts for tube-to-tube connections or structural joints (see Figure 1). The noncontact nature of the laser process allows for repeatable, high-speed cuts of various angles without inaccuracy, tool wear, or manual setups. Precise angles and arcs that mate together can be produced without grinding.By adding a tab to the coped cut, you can get fixture-free positional accuracy in both length and rotation. Tabs also can even be constructed to hold tube pieces together for welding.

3. Hole Cutouts
Laser processing allows you to program and create complex hole geometries in tubes and pipes (see Figure 2). Because laser processing is force-free, it does not create dimples. In addition, hard tooling and related setup times are eliminated, and you do not have to machine mandrels to match inside diameters.

4. Flow-type Joints
With a laser tube cutter, flow-type joints are programmed and then processed in one operation, creating good fit-up and reducing fabrication time. Laser cutting of these joints typically takes two to four seconds.

Figure 2
Lasers can be used to cut complex hole geometries in tubes and pipes without mandrels and without creating dimples.

5. Through-tube Projections
Through-tube projections for structural designs can be programmed without any manual calculations, and cut in one operation. You can choose your interface location and angle with the offline programming system and let the machine produce parts ready for assembly, without multiple setups.

6. Laser Marking
In addition to cutting tubes, a laser machine can also be programmed to laser etch the cut parts for identification purposes. Part numbers, serial numbers, or assembly instructions can be applied to each part, deep enough to be seen even after painting. Part marking can add value to each cut part by helping to eliminate assembly errors and streamline your manufacturing process.

Figure 3
Bayonets and dovetails can be programmed on a laser cutting machine and used for weld-free assemblies or as temporary holding aids for weld setups.

7. Locking Tube Connections
Locking tube connections are a design possibility with laser cutting. Two different types can be programmed: reusable temporary connections and permanent one-time-only locking connections. For example, bayonets and dovetails can be programmed on a laser cutting machine and used as temporary holding for welding setups (see Figure 3). In fact, laser-cut locking tube connections can strengthen mechanical assemblies, minimizing or eliminating the need for welding.

8. Hand Bend Preparations
Laser cutting also can be used to prepare tubes for hand bending operations. Cuts can be designed with knockouts, miter cuts, and bendable tabs that can be removed, allowing tube frames to be formed by hand (see Figure 4).

9. New Designs
Laser technology can open the door to new designs. One example of this is the oil industry's perforating gun, a long tube with through-holes cut at various rotational locations up and down the tube, into which explosive charges will be placed. This type of design requires a large amount of material to be removed from the tube, leaving only a thin web of material behind.

Figure 4
Laser cutting can prepare tubes for hand bending operations and eliminate weld setup time.

Another new design, the U-joint, is a flexible tube construction in which cutouts are removed to allow the remaining tube to fold at an angle to itself (see Figure 5). By repeating this pattern multiple times, you can create a bendable tube from a solid tube. U-joints can be positioned in a row to allow bending in one plane only or varied to allow multiplane flexing.

The spiral zipper tube design uses a puzzle-type interlocking weave that allows a solid tube to flex. One potential application for this technique is a situation in which torque is needed at off-axis positions.

10. Odd-shaped Tubes, Profiles, and Extrusions
In addition to the more common round, square, and rectangular tubing, a laser tube cutter also can process odd-shaped tubes and complicated profiles, such as C-channels, D-tubes, elliptical tubes, angles, extrusions, and bar stock. The unusual geometry can be programmed into the design software to allow the production of cutoffs, miters, holes, and tube-to-tube preparations as on ordinary tubing.

Figure 5
The U-joint is a flexible tube construction in which cutouts are removed to allow the remaining tube to fold at an angle to itself.

Dedicated laser tube cutting centers can simplify the creation of prototype and high-volume parts. Today's systems consolidate six or more machining operations and eliminate manual setups, hard tooling, and weld fixtures, offering today's tube fabricators a quick return on investment and a step toward modernizing and streamlining their manufacturing operations.

David Gilmore is a product engineer at TRUMPF Inc., Farmington Industrial Park, Farmington, CT 06032, 860-255-6046, fax 860-255-6421,,

David Gilmore

Contributing Writer

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The Tube & Pipe Journal

The Tube & Pipe Journal

The Tube & Pipe Journal became the first magazine dedicated to serving the metal tube and pipe industry in 1990. Today, it remains the only North American publication devoted to this industry and it has become the most trusted source of information for tube and pipe professionals.

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